The laboratory continues to work on a new strain of mycoplasma originated from the standard NIH-3T3 cell line after transfection with DNA isolated from AIDS patients' tissues. This agent, designated as Mycoplasma incognitus, was found to be infectious in cell culture, and in monkey to cause a waste syndrome, and death. Specific genetic clones and antibodies were obtained for this agent and was used to probe infected tissues. Attempts have been made to develop molecular and serological assays for the agent and to study the specific immunoresponse. These assays will be used to assess the significance of infectivity and pathogenicity of this agent in humans. Genetic analysis by a liquid hybridization procedure has shown that the DNA of this agent closely resembles M. fermentant. M. fermentant has been associated with leukemia previously. Coinfection with M. incognitus enhances the ability of HIV-1 to induce cytopathic effects on human T lymphocytes in vitro.